Arrangement of an electromagnet coupling gear

ABSTRACT

The electromagnetic clutch that serves for positive-locking assembly of concentric transmission shafts is inserted in a transmission housing (2) concentrically in relation to a shaft (1) and with a bushing (10) which externally encloses it, there resulting outside the bushing (10), in the area of the annular magnet (16), a free space that reduces the leakage, and the sliding sleeve (18) and the armature plate (19) together with the magnet (16) and eventual additionally provided bearings (25) can be preassembled, ready for operation and protected against damage. On the outer end of the bushing (10) can be provided at the same time a roller bearing (25) for the clutch part (24) that carries the counter gear (22) on the other shaft. Due to the design that reduces the leakage and the arrangement in the area of a seal gap also existing in the transmission housing (2), it is possible to work with clutches of small dimensions and a transmission housing (2) of equal size can be used optionally with and without inserted clutches.

The invention concerns an arrangement according to the preamble of claim1 and departs from U.S. Pat. No. 3,414,100. Said publication disclosedthe combination of separate parts of an electromagnet coupling gear toform a bushing with retaining flange in a manner such that their finalassembly is simplified by inserting in a transmission housing thebushing together with coupling elements preassembled therein. But thisknown coupling system still has disadvantages which hinder or makeimpossible their use, specifically for locks on axle transmissions.Thus, in the principle already known the armature must be alreadyassembled in the housing before there can be inserted the bushing inwhich only the magnet and a bearing have been preassembled. The armatureand another intermediate element with axial gearing on the shaft musthave been already assembled on the installation side before attachmentof a coupling wheel. Therefore, the engaging gear does not project fromthe housing on the input side and the armature is comprised by themagnet only on face end and not also peripherally and thus a sufficientmagnetic power can be transmitted only over an axial air gap to be keptrelatively small. Due to the consequently limited stroke, only low teethand thus only low torques are possible. The adjustment of the air playof the armature is here combined with the adjustment of the bearing.Besides, said coupling is disengaged under current and for this reasonis already inadequate for locks which must be opened currentless.

Electromagnet gear couplings such as disclosed, for instance, in WO86/022981 wherein ring magnet, sliding sleeve and armature are to beeach separately fitted in a transmission housing, result in expensiveassembly and installation conditions that take space and enlarge themagnetic stray flow. Higher electric performances then need in turnlarger structural elements and additional construction and materialcosts. Specially to enlarge and particularly to design a transmissionhousing for mounting an electromagnetic gear coupling of such kind isoften impossible, as for example, in standardize tubular housings suchas exist in axle transmissions.

The problem to be solved by the invention is essentially to provide inan insert bushing which can be preassembled as completely as possible,an electromagnet gear coupling, also adequate for optional use as lockactuation in one piece axle transmissions, which operates quickly andnoiselessly, wherein the engaging gear can be designed with sufficientlyhigh teeth and the coupling wheel is on the input side before thehousing and the armature on the output side in the housing in which theelectromagnet gear coupling can be inserted without impairing the airplay of the armature and without there being required in thetransmission changes worth mentioning in housing or installation.

The solution is obtained with the characteristic features of claim 1mainly insofar as the ring magnet surrounds a sliding sleeve axiallymovable on the shaft and which for its part has the armature in thecommon assembly on the output side but a radial engaging gear projectsfrom the housing on the input side. The assembly designed as bushing,completely ready for installation, is separately insertable in thehousing and can be fastened by means of a flange without it beingpossible for the air play of the armature to change in the process. Aradial support of the bushing with axial spacing from the magnet allowsa concentrating arrangement favorable to the magnetic flow, and ifadequate material is selected for the parts surrounding the magnet, itis possible with only a single and relatively small ring magnet toobtain within the bushing sufficient shifting and retaining forces.

If the sliding sleeve is slid directly on top of an outer spline of theshaft and there is added the opposing gear situated on the frontalsurface located on the engagement side of a further hub collar that actsas the external plate support of a frictional engagement device, thesliding sleeve can be held so as not to be able to turn upon the sameouter spline of the shaft in the same manner as is the inner platesupport of the frictional engagement device.

If the sliding sleeve is introduced so as not to be able to turn into aninner spline of a hub collar and there are added the opposed gear teethdisposed on the meshing side of the frontal surface of a further hubcollar that acts as an inner plate support for a frictional engagementdevice, the sliding bushing can be isolated from possible slidingmovements of the shaft which may, for example, occur in driven axles ofmotor vehicles. The frontal teeth, being then disposed on the smallerhub collar, are also easier to manufacture.

An annular collar extending radially beyond the sliding sleeve anddisposed axially between the magnet and the bearing not only can serveas a stop and thus preclude the need for a bushing end plate outside ofthe armature plate, but, given a magnet of suitable design can also beused as a counter armature during the resetting action or can accept onits front facing the mesh, either reset springs or stopping bolts.

By means of screw bolts located in the hub collar, the heads of whichbolts extend in the annular collar on the magnet side but are notmovable therethrough a finely adjustable end stop for the sliding sleevecan be produced in the direction of the opening without an end plate ofthe bushing.

Should an end plate for the bushing serving as a stop for the slidingsleeve in the direction of the opening be used, the space occupied bythe above-mentioned screw bolts for example, will be free to accept thereset springs.

If a plate is secured in the bushing so that it can be removed, such aplate can quite easily be produced from non-magnetic material for thepurpose of increasing the magnetic flux.

If, when the sliding sleeve occupies the open position, a certain airgap is created axially between the annular magnet and the annularcollar, not only is the magnetic flux improved, but the annular magnet,in the event the roller bearings become more severely compressed, isprevented from becoming a striking surface.

Reset springs arranged between the annular collar of the sliding sleeveand the opposite hub collar ensure that, when no current is flowingthrough the magnet, the drive gears will not accidentally engage.

A turned groove of suitable radial dimensions located in the frontalarea enables the particularly rigid support of the annular collar of thebushing inside the inner flange of the transmission housing, and doesnot necessitate a lengthening of the overall transmission housing.

The arrangement of the drive gears radially outside the reset springs,e.g. on the annular collar of the sliding sleeve, facilitates theconcentric installation of a single spring over the shaft, and the useof a particularly short sliding sleeve is made possible.

Should the armature plate be designed so that its diameter diminishes inthe direction on the annular magnet, and there be radially separated byan airgap from such armature plate, a magnetic ring situated inside thebushing and axially mounted between the plate and annular magnet, whoseinside diameter diminishes at approximately the same angle toward theannular magnet, the magnet flux will be improved and a more reliableengagement will be achieved in closing direction.

Oil channels, which surround the bushing inside the flange and aredisposed more or less parallel to the shaft in principal directionpermit the unimpeded axial flow of lubricant axially through the clutchzone which is specially important in axle transmission systems.

The virtually radial disposition of the annular magnet inside thebushing underneath the external flange permits a cable to be introducedinto the protective zone of the flange so as to avoid a weakening of thetransmission housing at exposed points.

The combination of the proposed electromagnetic clutch arrangement witha known shaft-driving differential gear can work to advantage in anumber of ways:

The clutch can, in any event, be inexpensively and reliably installed ina number of ways inside the axle casing.

Should the differential in question not be of the self-locking kind, asimple differential can be caused to become fully lockable. Should, onthe other hand, the differential be of the self-locking kind, the clutchwould not be set in motion with every little change in speed and, thusbecause its gears would not be overworked, would be able to providelonger-lasting service. Because full locking can be initiated by theclutches with the help of special sensors, it is also possible todecrease the locking coefficient of the differential and thus reducetire wear and the motive power required while at the same timemaintaining, due to the instantaneous engagement of all the wheelsthrough the electromagnetic clutch, complete braking reliability.

The arrangement according to the invention permits the structural meansfor the insertion of an electromagnetic clutch unit be limited to aninternal bearing area or a turned groove inside the inner flange of thehousing in question and thus precludes the need for different axlecasings with or without lockable clutch.

It is nonetheless also possible, e.g. in the case of axles, to provideboth tubular housing halves for the axles shafts for the purpose ofaccepting such bushings, and either let both work together with thedifferential, or insert in one of the halves, an electro brake ofessentially the same construction as that of the electromagnetic clutch.

The invention is not limited to the combination of features of theclaims. Other important possible combinations of claims and particularfeatures of the claims result for the expert according to the statedproblem.

The invention is described in detail herebelow with reference to threeembodiments according to the diagrammatic drawings.

FIG. 1 is a section through an electromagnetic clutch arrangement in apreassembled bushing, wherein the unengaged sliding sleeve is positivelylocked directly to the shaft it drives.

FIG. 1A is a detailed drawing of part of FIG. 1 showing a conicallyshaped armature plate for the purpose of facilitating start up.

FIG. 2 shows an alternative arrangement wherein the sliding sleeve isrotated about the hub of the coupling part independently of the drivenshaft before its frontal gear teeth are coupled with the hub of theshaft to be driven. Here is provided an axially adjustable stop in theopen position by means of screw bolts.

FIG. 3 shows an alternative arrangement of the drawing illustrated inFIG. 1 wherein the axial stop is disposed between the sliding sleeve anda plate of the bushing and closes the sliding sleeve against a resetspring.

In FIG. 1, a shaft 1 is surrounded by the tubular end of a transmissionhousing 2, on which an outer flange 3 on the tube side features a sealedjoint gap 5 for the purpose of connection with counter flange 4 ofanother housing half. Situated radially underneath flange 3 is an innerflange 6 in which oil channels 7 can be disposed more or less parallelto shaft 1 about the circumference. At least one cable duct 8 isarranged in flange 3 preferably radially in relation to the shaft inorder to connect with the magnet. A bushing 10, which can be insertedinto the opening of inner flange 6 in telescopic fashion andconcentrically to the shaft, can be axially fixed in a number of ways.In the example shown, bushing 10 possesses an outer annular collar 11that fits into a radially turned groove 9 so that the bushing 10 axiallyrequires no additional space for installation. Along approximately onethird of the length of bushing 10 is an inner annular shoulder 12produced from the same ferromagnetic material as bushing 10. The innerend of bushing 10 facing away from the mesh is formed by an annularplate 13, in this case axially secured in the bushing by means oflocking rings 14 and 15. An annular magnet 16 sits against inner annularshoulder 12 axially between plate 13 and the inner annular shoulder 12.In this connection, an axial air gap or clearance 17 remains opposite asliding sleeve 18 unturnable in a spline of the shaft but axiallyslidable and turnable in relation to the annular magnet 16, the end ofwhich sliding sleeve facing away from the mesh lies against plate 13when the clutch is in unengaged condition. Sliding sleeve 18 carries atthis end an annular armature plate 19 consisting of ferromagneticmaterial and also separated from the magnet 16 when the clutch isunengaged, such armature plate in the example given being axially fixedon the sliding sleeve 18 by means of a locking ring 20 and a radialturned groove situated on the side facing the magnet. On the end of thesliding sleeve 18 facing the mesh is a set of radial drive teeth 21,which, when current flows through the magnet 16 meshes with a similarcounter set of teeth 22 located on the magnet-facing frontal side of hub23 of any kind of clutch wheel 24. According to the example, a rollerbearing 25 is passed a short distance in front of counter gear teeth 22through hub 23 and concentrically to shaft 1. In this example, the outerring of the roller bearing is borne in the bushing 10 situated insideinner flange 6. In the example given, between shaft 1 and hub 23 islocated an annular space 27 in which, when the clutch is engaged, areset spring 26 coiled around shaft is axially preloaded between themesh-facing frontal side of the sliding sleeve 18 and a driven collar ortoothed gear 28. The electrical supply for the magnet 16 is providedthrough cables 29, 30 located in cable duct 8.

FIG. 1A illustrates an alternative possibility of control of thestarting power of electromagnet 16 wherein the armature 19A is axiallyfixed inside bushing 10 with an external diameter that diminishes in thedirection of magnet 16 and a magnetized ring 31 radially situatedthereabove that correspondingly increases in diameter toward magnet 16.Thus, an equal adjustment length will create a smaller air gap 32 forthe armature 19A that facilitate starting and save electricity.

The construction illustrated enables the elements of the electromagneticclutch, preassembled with a view to fulfilling any one of a number offunctions, to slide as a unified assembly that is protected againstdamage, through the open side of the housing flange assembly 3, 4 ontoshaft 1, without occasioning the need for either shaft 1 or transmissionhousing 2 to be modified.

In FIG. 2, sliding sleeve 18 inserted with an outer spline on the meshside into an inner spline of the driving hub 23, is not locked toshaft 1. In this case, however, hub 23 forms part of a propelling outerplate support of a frictional assembly 28A, due to wheel actuation by aninner plate support (28) locked to shaft 1 by means of a spline, thespeeds of the driving clutch part and of the shaft to be driven arematched with one another as much as possible before clutch 21, 22engages. In this connection, hub 23 extends clearly axially beyond gearteeth 21, 22. Between gear teeth 21, 22 and magnet 16, predominantlystill axially inside bushing 10, is arranged a spline for the slidingsleeve 18 and the hub 23. But sliding sleeve 18 could also betorsionally driven directly with the aid of screw bolts 33 that areaxially inserted into hub 23, whereby such screw bolts 33 fit axiallybetween magnet 16 and hub 23 through bores in an exteriorly extendingannular collar 18A of sliding sleeve 18. The screw bolts 33 if providedwith suitable length and heads of suitable size, can be designed torestrict the stroke length of sliding sleeve 18. Such an arrangementensures that, even when the clutch is open, the annular collar 18A willstill be separated from the annular magnet 16 by a residual air gap orclearance 17. When magnet 16 is excited, armature plate 19 that acts asan end plate for bushing 10, is drawn, upon sliding sleeve 18 whichcarries it towards magnet 16 until it grips clutch assembly 21, 22. Inthis embodiment, sliding sleeve 18, together with the clutch wheel 24,which may for example be the ring gear of a differential, are able torotate relative to shaft 1, and run synchronously therewith, if thegears 21, 22, are engaged. In this connection, the friction resulting inthe annular collar 11 of the bushing 10 can be reduced by means of abuffer disk provided in the inner flange 6 of the housing.

Such an embodiment also has, in relation to FIG. 1 the advantage thatthe electromagnetic stray currents reaching the shaft 1 are considerablyreduced, since the sliding sleeve 18 does not exhibit, up to the pointof gear engagement, a close magnetic affinity for shaft 1. To furtherstrengthen the electromagnetic effect, the screw bolts 33 as well as thespacing sleeves (not numbered) inserted therewith can be produced from anon-magnetic material. The sliding sleeve 18 remains uninfluenced bythis arrangement from the axial movements of the shaft 1, as they mostlyappear in the steering axle.

In FIG. 3, the sliding sleeve 18 also form-fits in the manner indicatedin FIG. 2 with clutch wheel 24 by means of the spline in hub 23. In thisexample, however, are shown methods of axially accomodating resetsprings 26A inside bushing 10 between hub 23 and annular collar 18A,which, according to the arrangement shown in FIG. 1 would have to beseparately slid directly on top of shaft 1. In addition, for the purposeof bolstering the magnetic force of magnet 16, a magnetized ring 31 isinstalled in the inner wall of bushing 10 on the side facing thearmature plate, which magnetized ring 31 works together by means ofparallel-conical surfaces with the armature plate 19 that forms the endof the sliding sleeve 18 facing away from the mesh. Should screw bolts33 be provided as stops on the open side, yet not in replacement ofindividual reset springs 26A, similar to FIG. 2, the here shown plate 13of bushing 10 is able to serve as a stop and prevent the passage of dirtfrom the axle transmission to the interior of the clutch.

Due to the fact that plate 13 is constructed of a non-ferrous metal, andbushing 10 is separated from transmission housing 2, and due to thearrangement that produces above magnet 16 an air gap about the freelyextending and presupported bushing 10, loss of magnetism through strayflux is minimized to the greatest extent possible, which in turn reducesthe electric power required for start-up. The openings in front of oilchannels 7 and the free space located between bushing 10 andtransmission housing 2 moreover permit cables 29, 30 to be installedwithout sustaining damage and without hampering the gear-lubricationsystem. The above-mentioned exemplified installation is not onlyapplicable to electromagnetic clutches but also for example tospecifically designed disk brakes. For example, it could be advantageousin the case of vehicular transmissions to provide the wheels withbifurcating axle casings for the optional installation of a housing ofthe proposed type, so that for example to one plug-in shaft could beattached an electromagnetic locking clutch of the type shown and to theoppositely situated plug-in shaft, a wet electro brake. The specialadvantage thus achieved is that when the brakes are applied, lubricatingoil flows radially through the spaces separating the brake disks towardhousing 2 into the annular gap surrounding bushing 10 and into oilchannels 7 of inner flange 6 to further cool the air-cooled outer jacketof housing 2.

1--shaft

2--transmission housing

3--flange of 2

4--opposite flange of 3

5--seal gap of 3, 4

6--inner flange of 2

7--oil channel in 2

8--cable channel in 2

9--turned groove in 6

10--bushing

11--annular collar of 10

12--inner annular shoulder on 10

13--plate of 10, buffer disk

14--outer locking ring of 13

15--inner locking ring of 13

16--annular magnet

17--air gap around 16

18--sliding sleeve

18A--annular collar on 18

19--armature plate

20--locking ring of 20

21--drive gear on 18

22--counter gear

23--hub

24--clutch part

25--roller bearing

26--reset spring

27--annular space in 24

28--collar, gear

28A--frictional assembly of 24 and 1

29--cable to 16

30--cable of 16

31--magnetic ring 10

32--air gap between 19 and 31

33--screw bolts in 28

I claim:
 1. An arrangement of an electromagnet gear couplingwhich has abushing (10) inserted in a housing (2) with a flange (3), said bushinghaving a ring magnet (16) preassembled therein for actuating an engaginggear (21) surrounding a shaft (1), and a coupling wheel (24 and 28) witha counter gear (22) being situated adjacent said engaging gear (21),characterized in that(a) said bushing (10) in addition to the ringmagnet (16) is joined together with an axially movable sliding sleeve(18) supporting said engaging gear (21) adjacent one end thereof andcarrying an armature disc (19) adjacent the opposite end of said slidingsleeve remote from the contact of the gears (21, 22) and thereby formsan operatively preassembled assembly, (b) said assembly being insertedin said bushing (10) concentrically with said shaft (1) to be coupled inthe area of a bearing (25) of said coupling wheel (24), (c) and saidengaging gear (21) being engageable, upon activation of said ring magnet(16), with said counter gear (22) mounted outside said bushing (10) on ahub (23) of said coupling wheel (24) which encloses said shaft (1). 2.An arrangement according to claim 1, characterized in that said bushing(10) supported in said housing (2) can be preloaded, via the externalring of said bearing (25) that guides the hub (23) into said housing(2), against the internal ring of said bearing lodged in said hub (23)in a manner such that adjustments of the housing flange connections (3,4) leave unaffected the axial spacings between said armature (19), saidengaging gear (21) and said ring magnet (16).
 3. An arrangementaccording to claim 1, characterized in that said bushing (10) isconnected, via a ring collar (11), with an inner flange (6) of saidhousing (2) and the ring collar (11), once installed, comes to liesubstantially radially over said bearing (25).
 4. An arrangementaccording to claim 3, characterized in that said inner flange (6) has aradial groove (9) for said ring collar (11) of said bushing (10) so thatthe latter is situated axially snugly relative to the front face on thecontact side of said inner flange (6) of said housing (2).
 5. Anarrangement according to claim 3, characterized in that between saidbushing (10) and the inner wall of said housing (2) there are providedoil ducts (7) extending substantially co-parallel with said shaft (1)and penetrating said inner flange (6) outside said bushing (10).
 6. Anarrangement according to claim 1, characterized in that said ring magnet(16) is inserted in said bushing and is situated substantially radiallybeneath the flange (3) of said housing (2) into which is worked a cableduct (8) for connecting cables (29, 30) of said ring magnet (16).
 7. Anarrangement according to claim 1, characterized in that said housing (2)is an axle housing and said hub (23) or said gear (28) that carries saidcounter gear (22) is supported on a differential transmission concentricwith said shaft (1), and said hub (23) acts as crown gear and said gear(28) as axle bevel gear and carries the inner ring of said bearing (25).8. An arrangement according to claim 1, characterized in that saidsliding sleeve (18) is non-torsionally guided on said shaft (1) by aninternal gearing engaging an external gearing of said shaft (1) and saidhub (23) is part of a friction connection (28A) which interacts withanother non-torsional collar (28) on said shaft (1), and means areprovided to connect said electromagnet gear coupling (16) periodicallyafter activation of said friction connection (28A).
 9. An arrangementaccording to claim 8, characterized in that said sliding sleeve (18) hasan external gearing which meshes in an internal gearing of said hub(23).
 10. An arrangement according to claim 8, characterized in thatsaid sliding sleeve (18) has, on an integrally formed ring collar (18A)radially projecting axially between the ring magnet (16) and the bearing(25), a stop in the disengaged direction of said gear coupling (21, 22)opposite an end face of said hub (23) or of an internal ring of saidbearing (25) fastened thereon and projecting on the contact side.
 11. Anarrangement according to claim 10, characterized in that said stopconsists of said ring collar (18A) interacting with expansion bolts (33)axially threaded in the end of said hub (23) on the contact side andinserted during preassembly.
 12. An arrangement according to claim 10,characterized in that an axial air gap (17) remains between said ringmagnet (16) and said ring collar (18A) of said sliding sleeve (18) inthe disengaged position.
 13. An arrangement according to claim 10,characterized in that at least one recoil spring (26) is supportedaxially between said ring collar (18A) of said sliding sleeve (18) and agear-free end face of one of said hubs (23, 28).
 14. An arrangementaccording to claim 13, characterized in that said gear (21) is situatedradially outside said recoil spring (26) on the end face on the contactside of said ring collar (18A) of said sliding sleeve (18).
 15. Anarrangement according to claim 8, characterized in that a disc-likebottom (13) axially closes said bushing (10) and said sliding sleeve(18) axially abuts against the dics-like bottom when said gear coupling(21, 22) is disengaged.
 16. An arrangement according to claim 15,characterized in that said disc-like bottom (13) is detachably fastenedin said bushing (10) and consists of non-magnetic material.
 17. Anarrangement according to claim 15, characterized in that said armaturedisc (19) consists of a ring disc (19A) which tapers in diameter in thedirection of said ring magnet (16) and which in a currentless state islocated, while keeping a conical air gap (32), radially outside a polering (31) which tapers in diameter at substantially the same angle inthe direction of said ring magnet (16) and which is axially clamped onthe inner side of said bushing (10) between said ring magnet (16) andthe dics-like bottom (13).